Rewrites the utility-process worker to drive pi-agent-core's Agent class
against pi-ai models and pi-coding-agent tools. The entry file keeps the
queue and cancellation state, delegates runs to WorkerRunner, and routes
RPC responses through WorkerRpcClient so beforeToolCall/afterToolCall
approvals and prepareRun credential resolution travel back to main's
RuntimeBridge. Worker message schema gains `agent-event` + `rpc-request`
envelopes, and run-finished no longer depends on the deleted sessionCodec.
Extract handleWorkerMessage (380 lines, 12 positional args) into dispatcher
+ focused handler modules. Dispatcher now routes by message.type to
run-log / run-status / run-finished handlers, each receiving (event, deps,
context) triple. run-finished is further decomposed into 5 steps:
finalizeRun, accumulateAndRotateSession, emitAndNotifyCompletion,
runPostCompletionAutomation, triggerSelfWake.
No behavior change: all branches, notifications, lease renewals, circuit
breaker, and escalation semantics preserved. Schema validation stays at
dispatcher top level.
The lock was previously claimed when the worker reported `running`, which
is after `agent.prompt` had already started streaming. Two concurrent
runs targeting the same workspace could both pass the main-side checks,
both get enqueued, and both read half-written state before one of them
lost the lock race and was cancelled mid-flight.
Move the `claimWorkspaceLock` call into `dispatchRunToWorker` so main
coordinates exclusivity authoritatively. If the lock is unavailable,
the run is finished as failed and never enqueued. The worker-side
lease-renewal path is preserved since it is a lease, not a lock.
ZacharyZhang-NY